Abstract: The Swedish party system has been one of the world’s most stable, and anti-immigrant parties have been largely absent from the centre-stage of Swedish politics. It is thus peculiar that an anti-immigrant party, the Sweden Democrats (SD), made a dramatic breakthrough in the 2006 local elections, gaining representation in 144 out of 290 municipalities. The purpose of this article is to explain why the SD gained representation in almost half of the Swedish municipalities. Results indicate support for a supply-oriented argument: whether the SD ran with a formal ballot or not has a substantial and statistically significant effect on their probability of receiving representation even when a series of variables, suggested by previous research, is controlled for. The result has important ramifications, since it implies that no obvious socioeconomic factors, e.g. local ‘fertile grounds’, brought SDs success about. Rather, what decided its fate was whether or not the party had an organizational presence and actual candidates running for seats.